So for Amazon it shows whether they are in stock by Amazon directly. Not necessarily other sellers selling through Amazon. A reason for this is a lot of sellers that are not Amazon directly jack up the prices for Lego sets. So they are considered by the system as "OOS". I'm planning on implementing a status and a price soon. But for instance take a look at the Super Star Destoryer on Amazon. Retail price by Amazon is $399 when they have it in stock. Currently the price is $799 by an outside seller listing it on Amazon.